This invention relates to woodworking devices for holding workpieces.. One of the oldest needs in the field of woodworking is the need to hold a workpiece. Solutions have been developed in great variety throughout the world, although it can be argued that eastern and western woodworking have followed different paths. Eastern woodworking typically uses somewhat simpler devices for holding workpieces, and woodworkers' feet are often directly involved. Western woodworkers typically work standing and have, by contrast, evolved the extensive use of clamping devices to hold workpieces. Examples of such devices include workbenches utilizing bench dogs, woodworking vises, hold-downs or panel clamps.
Numerous panel clamps also exist for clamping boards edge to edge in joining panels, including, among others, sash, bar and pipe clamps. Many of such existing clamps are excellent devices, but most are quite expensive and limited in the panel width they can accommodate. For instance, U.S. Pat. No. 4,671,500 issued to Mark discloses a "Double Acting Clamp." The Mark device uses guide plates for holding the material. A clamp is connected to each end of the guide plates by means of angled linkages that insert into notches on either side of the guide plates. See FIGS. 1-2, 4. Exertion of pressure through a jack screw 11 results both in a downward force against the guide plates and a side force against the material. Col 1, lines 62-8. The range of materials that can be clamped by a set of guide plates, however, is limited by the placement on the guide plates of notches for anchoring the linkages. Notches are placed on only the end of the guide plates, thus limiting the range of materials that can be accommodated by any one set of guide plates, and thereby requiring the user to purchase different sized guide plates.